Draw out type electrical switchgear with improved movable contact assembly mounting means

ABSTRACT

An oil-immersed circuit breaker comprising one or more pairs of arcuate fixed contacts, an equivalent number of arcuate bridging contacts insulated from and supported on a carrier structure, means mounting the carrier structure for pivotal movement about an axis remote from the fixed contacts and coaxial with the arcuate contacts, and operating means for moving the carrier structure pivotally to effect engagement and disengagement of the bridging contacts with the fixed contacts. The removable mounting means consists of an apertured plate on the movable bridging contact assembly which coincides with structure plate with studs. Nuts are threaded onto the studs to hold the movable bridging contact assembly in fixed relationship to the framework structure.

United States Patent 1 Caton g Sept. 3, 1974 [54] DRAW OUT TYPE ELECTRICAL 3,415,957 12/1968 Bliebtreu et a1. 200/8 A I HG AR WITH IMPROVED 3,469,043 9/1969 Wilson 200/50 AA MOVABLE CONTACT ASSEMBLY I MOUNTING MEANS Inventor: George Caton, llkley, England Assignee: Yorkshire Switchgear and Engineering Co., Limited, I Yorkshire, England Filed: Mar. 12, 1973 Appl. No.: 340,303

Foreign Application Priority Data Mar. 16, 1972 Great Britain 12483/72 us. zoo/s0 AA, zoo/294 Int. Cl. H0lh 9/00, H02b 1/10 Field of Search zoo/s R, s A, 10, 11 TC,

200/15, 17, 153 G, 153 11,153 S.C,162,163,

References Cited UNITED STATES PATENTS 3/1966 Bliebtreu et a1, 200/10 Primary Examiner-James R. Scott Attorney, Agent, or Firm-Stevens, Davis, Miller & Mosher [5 7] ABSTRACT l'An oil-immersed circuit breaker comprising one or more pairs of arcuate fixed contacts, an equivalent number of arcuate bridging contacts insulated from and supported on a carrier structure, means mounting the carrier structure for pivotal movement about an axis remote from the fixed contacts and coaxial with the arcuate contacts, and operating means for moving the carrier structure pivotally to effect engagement and disengagement of the bridging contacts with'the fixed contacts. The removable mounting means consists of an apertured plate on the movable bridging contact assembly which coincides with structure plate with studs. Nuts are threaded onto the studs to hold the movable bridging contact assembly in fixed relationship to the framework structure.

8 Claims, 3 Drawing Figures This invention relates to switchgear for high voltage electrical supplies.

The invention is particularly concerned with oilor gas-immersed electric circuit breakers provided with arc-quenching means. The term oil-immersed when used hereinafter is intended to cover immersion in oil, gas or in other insulating fluids contained in a suitable tank or enclosure. Conventional electric circuit breakers of this sort include one or more pairs of fixed contacts and a similar number of movable bridging contacts to make or break a circuit across each of the fixed contact pairs. An arc-quenching means is associated with either the fixed or the movable bridging electric circuit breakercomprises one or more pairs of arcuate fixed contacts, an equivalent number of arcuate bridging contacts insulated from and supported on a carrier structure, means mounting the carrier structure for pivotal movement about an axis remote from the fixed contacts and coaxial with the arcuate contacts, and operating means for moving the carrier structure pivotally to effect engagement and disengagement of the bridging contacts with the fixed contacts.

A pivotal structure supporting but insulated from the,

movable contacts and the means for moving this can be made more compact and comprehensively detachable than the customary combination of external mechanism and internal movable arrangement, and in particular can be made as a completely detachable assembly in the form of a relatively long lever with the pivot at one end and the operating means at the other to minimise the frictional effort required when operating on short circuit.

Preferably the pivotal axis of the carrier structure is designed to lie horizontally, and the carrier structure extends substantially vertically upwards from the axis 1 when the bridging contacts are in their disengaged position. An angular movement of about 20 to 30 between the engaged and disengaged positions is generally sufficient, and this fairly small angular movement facilitates a compact arrangement.

" It is desirable that an arc control device is mounted on the carrier structure for movement with the bridging contacts. Alternatively, an arc control device may be mounted on or around the fixed contacts.

Conveniently the carrier structure and operating means are mounted on a framework which is removably'mounted in a housing to which the fixed contacts are secured. Thus, the whole of the movable contact assembly and controls therefor can readily be removed from the housing for replacement or maintenance'p urposes.

A specific embodiment of a circuit breaker according to the invention is shown by way of example in the accompanying drawings in which:

FIG. 1 is a schematic side elevation, partly sectioned and with parts removed for clarity, of a circuit breaker;

FIG. 2 is a perspective view of part of the circuit breaker; and

FIG. 3 is a prospective view of the manner in which the removable framework structure is secured to the housing. I

The circuit breaker is contained in a housing 1 which is fitted with wheels 2 for easy movement. Projecting from one wall of the-housing are two sets of three horizontally aligned plugs, each plug being connected to a fixed contact mounted inside the housing 1. Thus, plug 3 of the first set has an associated fixed contact 4 and plug '5 of the second set has an associated fixed contact 6;

Pivotally mounted within the housing 1 for movement about an axis 7 is a carrier structure comprising a number of pairs of parallel insulating arms 8, each carrying movable contacts having bridge plates providing main contact surfaces 9 and 10, the movable contacts being engageable with the fixed contacts 4'and 6 respectively. Each of the fixed and movable contacts is of arcuate form, and the center from which the arcs are drawn lies on the axis 7. The fixed contacts are each made up of main contact setions 1 I, 12 respectively cooperating with the contact surfaces 9 and 10 on the movable contacts, and auxiliary arcing contact sections l3, l4 engageable with internal arcing contact sections 15 and 16 respectively on the movable contacts. The auxiliary arcing contact sections 15 and 16 on the movable contacts have an associated arc trap interrupting device 17 which may be of conventional form. As shown in FIG. 1 the pivotal axis 7 is horizontal and in the position where the movable and fixed contacts are disengaged the insulating carrier arms 8 extend upwardly substantially vertically from axis 7. To engage the movable contacts with the fixed contacts the movable contacts are pivoted clockwise through about 20. Movement of the movable contacts from the open positon, shown in the FIG. 1, to the closed position is effected by a system of levers, shown schematically only, by releasing the stored force in a number of parallel closing springs 19. These springs are capable of being charged into a compressed condition by .means of a handle l9a' connected to the springs by a further lever system and manually operable to compress the springs. Release of the springs 19 to close the movable contacts is under. the control of a manually operable; release catch 21. Movement of the handle 19a to charge the closing springs 19 also has the effect of charging springs v 20 which are effective when released to move the movable contacts from their closed position to their open position. The opening springs.20 are normally held in their charged position by engagement of a catch 22 with a lever 23, and disengagement of the catch 22 from the lever 23 allows the springs 20 to be released for pivoting the movable contacts to the open position. The catch 22 may be moved to release the springs by depressing a trip element 24 projecting through the upper wall of the movable housing. The lever system controlling the position of the movable contacts also drives two tappets and 26 projecting through the upper wall of the movable housing 1 and engaging opposite ends of a rocker arm 27. With the movable lowered and tappet 25 is raised.

The movable contact arms 8 and the lever system for controlling operation of these arms are all mounted on a frame which is removably mounted in the housing 1. The frame comprises side members 48, 49 welded at their upper ends to plates 50, 51 which are'welded in turn to a transverse frame member 52 supporting the lever system. The lower ends of the side members have holes through which a shaft 53 passes, the shaft being rotatable within the holes. The insulating arms 8 are secured to the shaft by plates 54, and the shaft is pivotally supported in a socket block 60 in the lower part of the housing. The frame is thus located in the lower part of the housing by thesocket block 60, and is secured at the top of the movable housing by four nuts such as 55 secured to studs projecting upwards from brackets 56 at the front corners of the housing, and passing through holes 57 in plates 50 and 51. v

As shown in FIG. 3, plate 56 extends from the rear wall of housing 1 and has studs 55a secured thereon; plate 50, fixed to side element 48, has holes 57 formed therein which coincide with studs 55a. Nuts 55 are threaded onto studs 55a and secure plate 50 to plate .56. Obviously only' one side is shown in the proposed the top of the movable housing it is possible to lift the frame out of the housing for maintenance of the movable contact and lever system; In orderto facilitatesuch removal the movable housing is fitted with a removable lid, which may be hinged to the body of the housing.

As is conventional the switchgear in the movable housing is immersed in an'oil bath which also partially covers the lever system. Whenever the switch is opened under short circuit conditions arcing at the contacts creates gas which must be released from the'movable housing. To enable this release, the removable lid is formed with an expansion chamber 28 leading into two vents 29, which can exhaust to-atmosphere.

"The lever system that is usedfor controlling the piv- I movable contacts. The trip element 24 provides mehousing 1 is located. In this way secondary electrical circuit elements may be omitted completely from the housing 1. This makes the arrangement as described herein particularly suitable for use in a switchgear as sembly as described in my co-pe'nding Application Ser. No. 340,263, filed Mar. 12, 1973.

What -I claim is:

1. A fluid-immersed circuit breaker apparatus, comprising:

a housing;

at least one pair of arcuately shaped fixed contact members;

means "securing said fixed contact members to said housing;

a framework structure;

means removably mounting said framework structure in said housing;

a carrier structure;

means pivotally mounting said carrier structure to said framework structure;

a plurality of arcuately shaped bridging contact members equal in number to said fixed contact members mounted on said carrier structure, wherein the centers of curvature of said arcuately shaped fixed and bridging contact members substantially coincide with the pivot axis of said carrier structure; and

operating means mounted on said framework structure for pivoting said carrier structure between a first position for engaging said fixed and bridging contact members and a second position for disengaging said said fixed and bridging contact members from each other.

2. A circuit breaker according to claim 1 and including an arc interrupting device mounted on said carrier structure for engagement with said bridging contacts.

structure for pivotal movement about a substantially horizontal pivot axis, and said carrier structure extends substantially vertically upwards from said axis insaid second position.

6.-A circuit breaker according to claim 5, in which said framework structure comprises substantially vertically extending side members and a transverse member joining said side members at their upper ends with said operating means being mounted on said transverse member; i

7. A circuitbreaker accordingto claim 6, in which said pivotal mounting meanscbmprises a shaft to which said carrier structure is secured, said shaft extending .ing 1 give'a mechanical indication of the position of the chanical means for opening the movable contact on de- V pression of the trip element. These three mechanically movable members may be used to control'mechanically, rather than electrically, secondary electrical circuits'positioned in a further housing beneath which-the between and rotatably mounted in lower ends of said side members, anda socket block secured in said housing and pivotallysupporting said shaft.

8. A circuit breaker according to claim 6, in which said side members are joined to said transverse member by plates formed with holes, said housing has studs located adjacent upper edgesofside walls thereof, and said holes in said' plates are fitted over said studs to locate' and secure the upper part of said framework in said housing.

claim 4 in which 

1. A fluid-immersed circuit breaker apparatus, comprising: a housing; at least one pair of arcuately shaped fixed contact members; means securing said fixed contact members to said housing; a framework structure; mEans removably mounting said framework structure in said housing; a carrier structure; means pivotally mounting said carrier structure to said framework structure; a plurality of arcuately shaped bridging contact members equal in number to said fixed contact members mounted on said carrier structure, wherein the centers of curvature of said arcuately shaped fixed and bridging contact members substantially coincide with the pivot axis of said carrier structure; and operating means mounted on said framework structure for pivoting said carrier structure between a first position for engaging said fixed and bridging contact members and a second position for disengaging said said fixed and bridging contact members from each other.
 2. A circuit breaker according to claim 1 and including an arc interrupting device mounted on said carrier structure for engagement with said bridging contacts.
 3. A circuit breaker according to claim 1 and including wheels rotatably mounted externally of the lower part of said housing and supporting said housing for horizontal movement.
 4. A circuit breaker according to claim 1 in which said pivotal mounting means pivotally supports said carrier structure at a first end thereof, and said operating means is pivotally connected to said carrier structure at a second end thereof.
 5. A circuit breaker according to claim 4 in which said pivotal mounting means supports said carrier structure for pivotal movement about a substantially horizontal pivot axis, and said carrier structure extends substantially vertically upwards from said axis in said second position.
 6. A circuit breaker according to claim 5, in which said framework structure comprises substantially vertically extending side members and a transverse member joining said side members at their upper ends with said operating means being mounted on said transverse member.
 7. A circuit breaker according to claim 6, in which said pivotal mounting means comprises a shaft to which said carrier structure is secured, said shaft extending between and rotatably mounted in lower ends of said side members, and a socket block secured in said housing and pivotally supporting said shaft.
 8. A circuit breaker according to claim 6, in which said side members are joined to said transverse member by plates formed with holes, said housing has studs located adjacent upper edges of side walls thereof, and said holes in said plates are fitted over said studs to locate and secure the upper part of said framework in said housing. 